In October a team of endurance athletes set a speed record on the Snowman Trek, a 188-mile trail through Bhutan’s high Himalayas that was originally a 17th-century Mongol-invasion route. They completed the trail in 15 days and 7 hours. That is fast considering the 97,131 vertical feet of elevation gain and loss — the equivalent of climbing up and down Everest four times. But in this hey-day of speed mountaineering it isn't that fast you say? You may be right. But then again, the likes of Ueli Steck and Karl Egloff aren’t ascending mountains with five cooks, 21 horses, and a foreign guide who thinks you're nuts.

Unlike other popular Himalayan trekking countries including Nepal, and even Tibet, the trails of the Kingdom of Bhutan remain largely unexplored. Part of the reason comes from a ban the country enacted in 1994 that prevents climbing any peaks above 6,000 meters (19,800 feet) out of respect for local spiritual beliefs. And part of it comes from Bhutan’s tight rein on tourism. They didn’t allow any tourists in until 1974 and even today there are restrictions, including the fact that foreigners are not allowed to travel alone in the country.

This turned out to be a major hitch for the team — consisting of Ben Clark, Timmy Olson, and Anna Frost — who had to book a guided package tour with a licensed Bhutanese Tour Operator. Then they had to figure out how to get their guides to keep up. The entourage that was forced on them consisted of one guide, five cooks, two horsemen, and 21 horses carrying food, water, and expedition gear. The guide, Wang Chuk, told Clark that 18 days was the fastest he could commit, and even then, he’d be forcing the staff to go without any breaks, moving twice as fast as the normal expedition pace. “I found out later that the more senior guides had left when they heard we were arriving,” says Clark. “They all thought we were insane.”

On the trail, Clark and team encountered relentless rain and snow that kept them constantly wet, and turned paths already churned up from horse hooves into knee-deep ravines of shoe-sucking mud. Temperatures dipped into the teens, resulting in some close calls with hypothermia. The altitude was a constant stressor, with 11 mountain passes topping 16,000 feet. A fourth teammate, Chris Ord, was forced to accept a medical evacuation after succumbing to pulmonary edema. But Clark says their most critical challenge was getting the Bhutanese crew to understand, and buy into, the speed-record goal.

“We tried to show by example, by being driven and motivated, and teaching techniques for how to go faster and lighter,” says Clark. “I think we mostly just drove everyone crazy.” In the end, it was Wang the guide who turned the tide. He gathered the crew and told them that they would make history with this trek.

Clark, 37, first envisioned setting a speed record on the Snowman Trek in 2012, when he was making the transition from high-altitude mountaineer to ultra-runner. He’d spent the previous 10 years making first ascents in the Himalayas, and setting records, including becoming the youngest person, at age 23, to lead a successful expedition up the north side of Everest. Clark was well aware of the fact that speed records were unheard of in Bhutan, but wanted to try. “Ever since I’d first learned of the Snowman Trek, I really wanted to check it out,” he says. “And setting a speed record seemed like one last thing I could accomplish in my Himalayas career before I officially retired.”